Short answer
Replace when the system is past about 12–15 years, uses R-22 and has a leak, or a repair costs more than about a third of a new system. Repair when it's under 10 years old and the failure is a single part like a capacitor, contactor or fan motor.
The age rule depends on climate
Long run hours shorten equipment life. A 15-year-old system in Phoenix, Las Vegas or Houston has worked as many hours as a much older one in a mild northern climate.
Refrigerant
R-22 is no longer produced. A large R-22 leak almost always tips the decision to replacement.
Efficiency and comfort
If some rooms never cool or bills keep climbing, a correctly sized new system with duct repairs may solve problems a repair can't.
- Ask for a Manual J load calculation
- Ask whether ducts will be tested
- Compare SEER2 ratings and warranties
Get it in writing
Ask for two options with model numbers, warranty terms and permit included, and verify the contractor's license with your state or local licensing authority.
Questions
How long do AC systems last?+
Often 12–17 years, and 10–15 years in very hot or coastal climates, depending on maintenance, sizing and installation quality.
Editorial note: this guide is general information for homeowners, not a diagnosis. Desertline Heating & Air is a referral service; a licensed contractor should inspect your equipment before repairs.